Internal combustion engines have been used for well over a century to power vehicles such as automobiles, trucks, buses, boats, motorcycles and the like. Such internal combustion engines typically include multiple cylinders in which a mixture of fuel and air combust to produce the energy and power required to propel a vehicle. A byproduct of the internal combustion process is exhaust gas that collects in each cylinder. An exhaust manifold is typically secured to the engine to collect the exhaust gases from the cylinders and channel the exhaust gases to the vehicle's exhaust system. Exhaust manifolds are typically one-piece cast iron or stainless steel systems. Some aftermarket exhaust manifolds, commonly known as headers, can include a series of tubes, with one tube dedicated to each cylinder. The tubes typically converge into a single tube called a collector. There is a need for improved headers that provide a user with the flexibility to use various sized and shaped tubes to remove exhaust gases from the cylinders of an engine.